This invention relates to control of an air conditioner, and more particularly to a control system for an air conditioner suitable for controlling indoor units according to operation control programs supplied to the indoor units.
JP-A-Hei2-110246 and JP-A-Hei2-101342 each describe an air conditioner having indoor units and an outdoor unit which are connected.
In the control system of a conventional air conditioner, a control device containing a microcomputer is mounted in each of the outdoor and indoor units, and the operation of the air conditioner is controlled by exchanging control information through communication lines between the outdoor unit and the indoor units.
For example, in a single-type air conditioner comprising an outdoor unit 20 and an indoor unit 21 as shown in FIG. 1, a communication line 17 is used for connection between those units. In a multi-system air conditioner comprising one outdoor unit 22 and a plurality of indoor units 23A to 23D as shown in FIG. 2, a plurality of communication lines 17A to 17D are used for connection with the indoor units 23A to 23D.
Generally, in an air conditioner of this kind, operation programs prepared respectively for the outdoor and indoor units are written in their read only memories (hereafter referred to as ROM). Those ROMs are mounted on the printed circuit boards in the control devices of the outdoor and indoor units.
Among others, in a system in which respective ROMs having indoor and outdoor operation control programs written therein are mounted on the printed circuit boards in the control devices of the outdoor and indoor units, there is a problem as described below.
(a) If the range of program modification made to rectify program defects or for functional improvement extends over the outdoor unit side and the indoor unit side, the ROMs of the control devices on the outdoor and indoor unit sides need to be replaced with ROMs in which modifications have been made. Even if the range of program modification is limited to the indoor unit side, in contrast to a single-system air conditioner having only one indoor unit, in the case of a multi-system air conditioner, the printed circuit boards in the control devices of all the indoor units must be replaced, which require great amounts of work and expenses attending on the program modifications.
(b) Even when the whole system has been changed in a model change, even though the hardware of the indoor units is compatible with both the old and new systems, if the operation control program is not compatible with the old and new systems, the air conditioner cannot be operated by a combination of a new outdoor unit and old indoor units or a combination of an old outdoor unit and new indoor units.
(c) Even when the indoor-unit hardware is compatible with both a single-system air conditioner and a multi-system air conditioner, if the operation control program is not compatible with both systems, it is impossible to operate in combination a single-system outdoor unit and multi-system indoor units or a multi-system outdoor unit and a single-system indoor unit.